Stir together garlic, turmeric, cayenne, cumin, coriander and 1 teaspoon water to make a thick paste. Using a fork, mix together onion and canola oil, crushing onion slightly. Mix spice paste into onion.

Over medium heat, bring coconut milk and 2 1/2 cups water to a boil. Immediately reduce to a simmer. Stir onion mixture into coconut milk, making sure that the spice paste is well distributed. Add okra and salt, stir and simmer, uncovered, until okra is tender, about 30 minutes.

Add pureed tomato and serrano. Simmer for 5 minutes. Add the shrimp and simmer only until shrimp are cooked, another 5 minutes. Stir in vinegar and simmer for a few minutes more. Taste and adjust the salt, if needed.

Note: If you don't like your curry soupy, which this is, boil it down before adding the shrimp. Increase the amount of okra if you wish. Serve with steamed rice.